1. Field of the Invention
The present invention relates to a piezoelectric vibrator, and more particularly, to a piezoelectric vibrator which makes an elliptical motion by combination of vibrations in a longitudinal mode and a flexural mode.
2. Description of the Related Art
Recently, ultrasonic motors using piezoelectric vibrators are drawing attention as new kinds of motors replacing electromagnetic motors. The ultrasonic motors using the piezoelectric vibrators have various advantages such as high resolution of displacement, silent operation due to absent of gear mechanisms, and low electromagnetic noise generation.
FIG. 1 is a schematic view illustrating a structure of a conventional piezoelectric vibrator 10.
As shown in FIG. 1, the piezoelectric vibrator 10 is divided into four vibration sectors 11, 12, 13 and 14, and has external electrodes 21 and 22 made of wires for applying alternating voltages of the same phase to two of the vibration sectors 11 and 14, 12 and 13 disposed diagonally from each other.
In addition, the piezoelectric vibrator 10 has a protrusion 30 at a side thereof for transferring driving power to the outside.
However, it is difficult to miniaturize such a conventional piezoelectric vibrator 10 having the external electrodes 21 and 22, requiring a space for installing the wires, thus complicating the manufacturing processes and obstructing mass production.
Therefore, there has been a need for a piezoelectric vibrator with a simple structure, which is suitable for miniaturization while facilitating manufacturing processes.